After various die have been created on a wafer, they must undergo die preparation, during which the die is prepared for integrated circuit (IC) packaging and testing. The die preparation process typically consists of wafer mounting and die cutting, followed by a die attachment step. The die is attached to a die pad or die cavity of a support structure (e.g. the leadframe) of a semiconductor package. The way the die is bonded defines the die attachment process. Soft solder and solder paste, applications are typically used in automotive and high-power devices. As an example, during a soft solder or solder paste attachment process, a solder material is used to bond the die to the leadframe. During a soft solder attachment process, solder is introduced as a wire preform and melted onto the hot leadframe surface as a liquid solder dot. During a solder paste attachment process, solder is dispensed on the leadframe through a small syringe. The die is then placed onto the solder, heated above melting point then cooled providing a solid connection.
Current back-end metal processes include depositing a layer of gold and a barrier material on the wafer prior to dicing or singulation. The classic wafer dicing approach employs saw blades to cut straight lines through device arrays, resulting in an exposed gold layer at the singulation cut point. During the soft solder attachment process, the exposed portion of the gold layer is dissolved into the solder resulting in loss of adhesion and the formation of large voids within the solder bulk. A typical gold loss is 30% due to gold dissolution or leaching into the solder.
Accordingly, it is desirable to provide a method for packaging semiconductor devices that results in reduced solder voiding and improved adhesion of the semiconductor die. In addition, it is desirable to provide a method for packaging semiconductor devices that provides a device with improved thermal performance. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.